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J Sci Med Sport. 2019 Mar;22(3):353-360. doi: 10.1016/j.jsams.2018.08.016. Epub 2018 Aug 30.

The effects of caffeine ingestion on isokinetic muscular strength: A meta-analysis.

Author information

1
Institute for Health and Sport (IHES), Victoria University, Australia. Electronic address: jozo.grgic@live.vu.edu.au.
2
Institute of Coaching and Performance, School of Sport and Wellbeing, University of Central Lancashire, UK; Exercise and Nutritional Genomics Research Centre, DNAFit Ltd, UK.

Abstract

OBJECTIVES:

The aims of this paper are threefold: (1) to summarize the research examining the effects of caffeine on isokinetic strength, (2) pool the effects using a meta-analysis, and (3) to explore if there is a muscle group or a velocity specific response to caffeine ingestion.

DESIGN:

Meta-analysis.

METHODS:

PubMed/MEDLINE, Scopus, and SPORTDiscus were searched using relevant terms. The PEDro checklist was used for the assessment of study quality. A random-effects meta-analysis of standardized mean differences (SMDs) was done.

RESULTS:

Ten studies of good and excellent methodological quality were included. The SMD for the effects of caffeine on strength was 0.16 (95% CI=0.06, 0.26; p=0.003; +5.3%). The subgroup analysis for knee extensor isokinetic strength showed a significant difference (p=0.004) between the caffeine and placebo conditions with SMD value of 0.19 (95% CI=0.06, 0.32; +6.1%). The subgroup analysis for the effects of caffeine on isokinetic strength of other, smaller muscle groups indicated no significant difference (p=0.092) between the caffeine and placebo conditions. The subgroup analysis for knee extensor isokinetic strength at angular velocities of 60°s-1 and 180°s-1 showed a significant difference between the caffeine and placebo conditions; however, no significant effect (p=0.193) was found at an angular velocity of 30°s-1.

CONCLUSIONS:

This meta-analysis demonstrates that acute caffeine ingestion caffeine may significantly increase isokinetic strength. Additionally, this meta-analysis reports that the effects of caffeine on isokinetic muscular strength are predominantly manifested in knee extensor muscles and at greater angular velocities.

KEYWORDS:

Caffeine; Exercise; Muscles; Power; Torque

PMID:
30217692
DOI:
10.1016/j.jsams.2018.08.016
[Indexed for MEDLINE]

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